Acid nickel electroplating bath



United States Patent f 3,305,462 AEHD NICKEL ELECTROPLATING BATH Bartlet D. flstrow, 125 Redwood Drive, and Fred I. Nobel, 75 Fern Drive, both of Roslyn, N.Y. 11576 No Drawing. Filed Sept. 2, 1965, Ser. No. 484,767 8 Claims. (Cl. 2041-49) This application is a continuation-in-part of our copending application Ser. No. 730,251, filed April 23, 1958, now Patent No. 3,219,559.

The present invention relates to the deposition of bright nickel deposits from acid baths, and more particularly to deposits of exceptional smoothness.

Prior nickel electroplating baths have resulted in relatively bright deposits, but in conjunction therewith certain difiiculties and disadvantages were encountered. In some, the rate of brightening was comparatively slow. Those baths which exhibited rapid brightening rates tended to produce brittle deposits. Numerous addition agents tended to produce low current density grayness, whereas others tended to produce skip plate.

It is among the objects of the present invention to overcome the difficulties and disadvantages inherent in the prior art and to provide an additive and a combination of additives to acid nickel plating baths which will have a high degree of leveling in the plating operation and over a wide range of current densities.

It is also among the objects of the invention to provide an additive to the bath which will eliminate the tendency for the formation of gray deposits, and which will give bright deposits even in the low current density areas, the deposits being ductile.

It is further among the objects of the invention to provide an additive consisting of several constituents which cooperate to give a synergistic result, providing deposits which are commercially desirable and acceptable.

In practicing the invention, there is provided a bath of nickel chloride, sulfate or sulfamate or mixtures thereof, such as is common in the art. A typical Watts electroplating bath is as follows:

G./l. NiSO,.6H O 300 NiCl .6H .O 45 Boric acid 45 Na lauryl sulfate .20

The invention is based primarily upon the conception that a certain type of acetylenic ethoxy alcohol, when added to said nickel plating baths in quite small quantities, will result in substantial improvement in the deposited metal. The compounds have the following structural formula:

whereon R is a radical taken from the class consisting of H, CH CH (CH )x, O(C H.,O),,H, and CH O(C H O) I-I; R is taken from the class consisting of H, CH (CI-I phenyl, cyclohexyl, naphthyl, O(C H O) H and CH O(C H O) H; Z is taken from the class consisting of H and halogen; n is 0 to y is 2 to 10; and x is 0 to in amounts from about 0.005 to 5.0 grams per liter. Preferably, n=+y equals about 10.

To be most effective, these compounds should have the triple unsaturation bond in the alpha position. For instance, the use of an amount thereof as little as 0.005 gram per liter of the ethylene oxide adduct in a Watts bath gives a bright plate with satisfactory leveling. The ethylene oxide adduct of methyl butynol having two 3,305,452 Patented Feb. 21, 1967 mols of ethylene oxide or more gives highly satisfactory brightening and leveling.

In addition, the addition agent has been found to yield highly satisfactory brightening and leveling.

It is desirable to have present at least one other additive. Such additional substances are certain sulfonamides and sulfonimides. It is also desirable to have present aromatic sulfonic acids having one or more sulfonic groups. These constituents may be present in the bath in quantities varying over relatively wide limits, but for best results comparatively large amounts of the sulfonamides or sulfonimides are used with only small amounts of the acetylenic glycols. Varying the proportions of the constituents may enhance one physical property over another. For example, with higher concentration of acetylenic ethoxylated glycols leveling may be still further improved with some reduction in covering power.

The sulfonamides and sulfonimides are well known compounds; they include the disulfonamides and disulfonimides. It is possible to use aliphatic or aromatic derivatives; however, the most commonly known compounds are those of benzene and naphthalene. They may have substituent groups which are inert in the bath and which do not adversely affect the solubility of the compounds. They are used in the bath in amounts from about 0.2 gram per liter to saturation and the larger amounts are not detrimental to the operation.

Among the sulfonic acids, it has been found that methylene bisnaphthalene or benzene sulfonic acids together with a sulfonamide or sulfonimide produce improved brightness and leveling when used in conjunction with the ethoxylated acetylenic alcohols. The amounts of these substances may vary widely and as little as 0.05 gram per liter has been found suflicient to exert their beneficial effect.

To produce the desired ductility and the desired characteristics of the deposit, a definite relationship between the sulfonamide or sulfonimide and the bis-sulfonic acid exists. Also, it should be noted that when the sulfonamide or sulfonimide is replaced by other well-known primary brighteners such as benzene sulfonic or disulfonic acids, naphthalene (mono, di or tri) sulfonic acids or their salts, no improved results occur. Deposits tend to be brittle and have a poor degree of leveling. Up to grams per liter of the present compounds are usually used but higher amounts may be incorporated in the additive to the bath.

The acetylenic glycols may be used in varying amounts. However, it is preferable to have present from about 0.005 gram per liter when the number of ethoxy groups is small and up to 5.0 grams per liter when the number of these groups is large. It is also preferable to have a maximum of 10 mols of ethylene oxide attached to the OH groups of the diol and such ethylene oxide may be variously distributed between these groups. A minimum of 2 mols, and preferable 4 mols appear to give the best results.

The following are a number of specific examples of additives to be introduced into the usual acid nickel plating baths, as illustrating the broad scope of the compounds and the proportions which have been found acceptable, the amounts being stated in grams per liter:

3 Example 1 O-benzoyl sulfonimide Na 1.0 Na styrene sulfonate 0.5 2-methyl-3-butyne-2-polyethylene glycol 274 pH 2.5-4.0, temp. 140 F. 0.03

Example 2 Dibenzene sulfonamide 1.0 Methylene bis-naphthalene sulfonate 5.0 2-methyl-3-butyne-2-polyethylene glycol 172 0.04 Example 3 Na naphthalene disulfonate 8.0 Benzene sulfonamide Na 1.0 Na styrene sulfonate 0.7 2-methyl-3-pentyne-2-polyethylene glycol 362 0.07 Example 4 Benzene sulfonamide 1.0 Na vinyl sulfonate 0.5 2-rnethyl-3-pentyne-2-polyethylene glycol 186 0.03 Example 5 Saccharine 1.0 Methylene bis-naphthalene sulfonate Na 4.0 N,N,N, ,N propargyltriethylene tetramine 0.02 2-methyl-3-butyne-2-polyethylene glycol 348 0.08 Example 6 p-Toluene sulfonamide 0.5 Benzene sulfonic acid Na 15.0 Vinyl acetate-tetraethylene pentamine reaction product 0.005 2-ethyl-3-butyne-2-polyethylene glycol 186 0.06 Example 7 O-benzoyl sulfonimide 1.0 Na allyl sulfonate 0.5 2-rnethyl-4-chloro-3-butyne 2 polyethylene glycol Example 8 Na toluene sulfonamide 1.0 Methylene bis-naphthalene-Na-sulfonate 0.7 1-propyne-3-polyethylene glycol 232 0.03 Example 9 2-methyl-3-butyne polyethylene glycol 260 0.05

All the ethoxylated acetylenic alcohols produce bright deposits, those with 2 or more moles of ethylene oxide give improved leveling and a lesser tendency towards 'skip plate. With 2-methyl butynol, increasing the number of moles of ethylene oxide above 8-10, will result in a product exhibiting oily or greasy characteristics which will produce non-uniform, poorly-leveled bright plate. For best commercial operation, the compounds having 2-6 moles of the ethylene oxide and the highly desirable 2-4 moles of the ethylene oxide adduct of methyl butynol, are the most practical.

What is claimed is:

1. In an aqueous acid nickel plating bath selected from the class consisting of chlorides and sulfates, the improvement which is an addition agent in said bath have the following formula:

R1 Rr-CECZ (Cz 4 )y wherein R is a radical taken from the class consisting of H and CH (CH )x; R is taken from the class consisting of H and CH (CH )x; Z is taken from the class consisting of H and halogen; y is 2 to 10; and x is 0 to 20; in amounts from about 0.005 to 5.0 grams per liter.

2. A nickel plating bath according to claim 1 in which there is also present a sulfonimide.

3. A nickel plating bath according to claim 2 in which said sulfonimide is present in amount of about 0.2 gram per liter to saturation.

4. A nickel plating bath according to claim 1 in which there is also present a sulfonamide.

5. A nickel plating bath according to claim 1 in which there is also present a sulfonamide in amount of about 0.2 gram per liter to saturation.

6. A nickel plating bath according to claim I in which there is also present an aromatic sulfonic acid.

7. A nickel plating bath according to claim 1 in which there is also present a sulfonic acid, in amount of about 0.05 to grams per liter.

8. In an aqueous acid nickel plating bath selected from the class consisting of chlorides and sulfates, the improvement in said bath which is the addition agent CH1 n-b-ozo-onr-on (IXCHLOMH in an effective amount sufficient to produce brightness.

References Cited by the Examiner UNITED STATES PATENTS 2,662,853 12/1953 Ellis 204-49 2,712,522 7/1955 Kardos et al 204-49 2,782,155 2/1957 DuRose et al. 204-49 2,849,353 8/1958 KardOs 204-49 2,852,449 9/1958 Becking ct al. 204-49 2,882,208 4/1959 Becking et al. 204-49 2,891,979 '6/1959 Ford et al. 204-49 X FOREIGN PATENTS 542,292 11/1955 Belgium.

JOHN H. MACK, Primary Examiner,

HOWARD S. WILLIAMS, G. KAPLAN,

Assistant Examiners. 

1. IN AN AQUEOUS ACID NICKEL PLATING BATH SELECTED FROM THE CALSS CONSISTING OF CHLORIDES AND SULFATES, THE IMPROVEMENT WHICH IS AN ADDITION AGENT IN SAID BATH HAVE THE FOLLOWING FORMULA: 